The clown standing in the way of George Birkbeck, 22 on his way home from the shops in Plymouth

Commander Julien Bennett of the Met Police also said: "Our primary responsibility is identifying and investigating those incidents where a criminal offence has occurred.

"However, anti-social behaviour can leave people feeling scared, anxious and intimidated and I would urge those who are causing fear and alarm to carefully consider the impact their actions have on others.

"In the run up to Halloween it is expected that these types of incidents will increase but with the launch of our annual Autumn Nights campaign in the coming weeks Safer Neighbourhood Officers working in partnership with other agencies will be carrying out additional reassurance patrols and will be on hand for those who are especially vulnerable during this period.

"Whilst we do not want to stop people from enjoying themselves it is important that while having fun they remember to act in a responsible manner and understand that they could be prosecuted if a criminal offence is committed."

She explains that as children we are familiar with the appearance of our caregivers and family members and we see them as having a “safe and friendly human face”.

“Our brain has to match patterns in order to survive. We need to be able to recognise and distinguish friendly (human) faces,” said Dr Melanie.

“Clown faces are quite different from this, they have unnatural, large, exaggerated and distorted features and therefore don’t match the ‘safe, friendly human’ pattern we have created in our minds.

“We know that clown faces are brightly coloured, with stark contrasts – for example wide bright red lips, against a very white background, with exaggerated smiles or expressions which are fixed and do not change with interaction.

“This triggers an ‘unsafe/ does not match’ alert in our primal brains which indicates this type of face is unknown, not recognised, possibly unsafe, possibly a threat and we cannot read the facial expression correctly as it doesn’t match the actions or words.”

This inability to interact with the clown means that we feel potentially under threat and feel fearful, panicky and threatened.

Dr Melanie explains that this usually causes us to avoid them altogether and if something is continually avoided the brain is likely to categorise it as ‘life threatening and dangerous’.

She said: “Generally, clown fears are set up in childhood and continue into adulthood.

“As with most other fears and phobias they can be treatable with modern therapeutic techniques such as Cognitive Behaviour Therapy, Relaxation therapy and guided imagery, Hypnotherapy or a combination.